Wheel cylinder, backing plate connection



Feb. 1, 1966 R. T. BURNETT 3,232,391

WHEEL CYLINDER BACKING PLATE CONNECTION Filed NOV. 8. 1961 '7'Sheets-Sheet 1 INVENTOR.

RIC/{20 7- BURNETT m 2. W

ATTORNEY Feb. 1, 1966 R. T. BURNETT WHEEL GYLINDER BACKING PLATECONNECTION 7 Sheets-Sheet 2 Filed Nov. 8. 1961 BY wumvazfl u ATTOR EYFeb. 1, 1966 R. T. BURNETT 3,232,391

WHEEL CYLINDER BACKING PLATE CONNECTION Filed Nov. 8. 1961 ts-Sheet sINV EN TOR.

RIC/1:030 T BURNETT ATTORNE Y Feb. 1, 1966 R. 'r. BURNETT 3,232,391

WHEEL CYLINDER BACKING PLATE CONNECTION Filed Nov. 8. 1961 y /Z l mINVENTOR. RICHARD T BURNETT AT TORNE Y 7 Sheet s-Sheet 4 Feb. 1, 1966 R.T. BURNETT WHEEL CYLINDER BACKING PLATE CONNECTION Filed Nov. 8. 1961 '7Sheets-Sheet 5 Ir? 5H.

[IIIIIII II/IIIII 2 mi' i m 4/4 INVENTOR.

RICHARD 7- BURNETT ATTORNEY Feb. 1, 1966 Filed Nov. 8,

R. T. BURNETT WHEEL CYLINDER BACKING PLATE CONNECTION 7 Sheets-Sheet 6IIIIIIII; 4

INVENTOR.

ATTORNEY Feb. 1, 1966 R. T. BURNETT 3,232,391

WHEEL CYLINDER BACKING PLATE CONNECTION Filed Nov. 8. 1961 '7Sheets-Sheet '7 I N VENTOR.

ATTORNEY United States Patent ()filice 3,232,391 Patented Feb. 1, 19663,232,391 WHEEL CYLINDER, BACKING PLATE CONNECTION Richard T. Burnett,South Bend, Ind, assignor to The Bendix Corporation, South Bend, Ind, acorporation of Delaware Filed Nov. 8, 1961, Ser. No. 150,929 9 Claims.(Cl. 188152) This invention relates to a brake assembly and componentstherefor.

More particularly the invention concerns a backing plate, a wheelcylinder housing, a wheel cylinder, backing plate connection, and aparking brake actuating mechanism.

The usual brake assembly most commonly employed on present day vehiclesrequires an anchor pin, an anchor reinforcement plate and a shoe guideplate. The anchor reinforcement plate must be welded to the shoe side ofthe backing plate and sometimes another anchor reinforcing plate iswelded to the back side of the backing plate. Then the anchor pin isinserted through a hole in the reinforcing plate and backing plate and ariveted head is formed on the anchor pin on the back side of the backingplate. These parts and the method of securing the anchor pin and anchorreinforcing plate to the backing plate are unduly costly when comparedto the total cost of a brake assembly.

It is an object of the present invention to provide a brake assemblywhich will be less expensive to produce and still be an improvement overthe commonly used brake assemblies of this general type.

Another object of the invention is to provide an improved backing platewhich has supporting surfaces for the web of a shoe closely adjacent theanchor.

It is an additional object of the invention to provide an improvedoneapiece backing plate having supporting surfaces thereon for slidableengagement with the webs of the brake shoes of the brake assembly andalso having an integral projection serving as an anchor for the brakeshoes.

A further additional object is to provide a backing plate, wheelcylinder combination wherein the backing plate and wheel cylinder areconnected to each other through interlocking portions.

A further object of the invention is to provide a wheel cylinder backingplate connection wherein the wheel cylinder has a boss extending into aslot of the backing plate and a locking plate is interposed between theupper edge of the slot and the wheel cylinder and bears against saidwheel cylinder.

Another important object of the invention is to provide a wheel cylindermounting backing plate connection with a locking plate that not onlylocks the wheel cylinder into position but also extends over the shoeends adjacent the anchor to prevent excess axial movement of said shoeends.

It is another object of this invention to provide a wheel cylinderhousing especially adapted for interlocking engagement with a brakebacking plate.

It is still a further object of the invention to provide a parking brakelever assembly for a brake which will produce a force component on thebrake shoes toward the backing plate.

Another object of the invention is to provide a parking brake leverwhich engages a brake shoe and transmits a force component on the brakeshoe toward the backing plate and transmits a force component on theother brake shoe toward the backing plate through an inclined strutconnected to the parking brake lever and said other brake shoe.

The above and other objects and features of the invention will appearmore fully hereinafter from a consideration of the followingdescription, taken in connection with the accompanying drawings whereinthe embodiments of the invention shown therein are illustrated by way ofexample.

FIGURE 1 is a front view of a brake assembly of the present invention;

FIGURE 2 is a front view of the backing plate;

FIGURE 3 is a section view taken on line 3-3 of FIGURE 2;

FIGURE 4 is a section view taken along line 4-4 of FIGURE 2;

FIGURE 5 is a section view taken along line 55 of FIGURE 2;

FIGURE 6 is a section view taken along line 6-6 of FIGURE 1;

FIGURES 6A-6N illustrate different modifications of the anchor;

FIGURE 7 is a section view taken along line 77 of FIGURE 1 illustratingthe wheel cylinder, backing plate connection;

FIGURE 7A is an isometric view of the locking plate of the wheelcylinder, backing plate connection;

FIGURE '73 is a modification of the wheel cylinder, backing plateconnection illustrated in FIGURE 7;

FIGURE 7C is a partial front view of FIGURE 7B;

FIGURE 8 is a section view taken along line 8-8 of FIGURE 1 illustratingthe parking brake lever arrangement;

FIGURE 9 is a section view taken along line 99 of FIGURE 8; and

FIGURE 10 is a view similar to FIGURE 7, without the wheel cylinder,which illustrates an embodiment of the invention wherein the backingplate is connected to a spindle at the anchor projection.

A preferred embodiment of the brake assembly of the invention isillustrated in FIGURE 1 with the pertinent detailed features beingillustrated in the other figures.

With reference to FIGURE 1, the brake comprises a backing plate 10,which constitutes part of the invention having holes 11 receiving boltsto mount the backing plate on an appropriate part of a vehicle such, forexample, as the axle flange, not shown. The backing plate has an anchor12 formed integrally therewith and while illustrated as round, may be ofany shape such, for instance, oval or square. Brake shoes 14 areslidably mounted on the backing plate 10 and have their ends 16 and 18interconnected by adjusting strut 2% The opposite shoe ends 22 and 24are spread apart by fluid motor 26 secured to the backing plate by meansto be described hereinafter. The fluid motor includes a pair ofoppositely acting pistons, not shown, operatively connected to the twoends 22, 24 through force transmitting links 28. Actuation of thepistons applies a force to each of the links tending to move the shoestoward a rotatable drum 36 which may be secured to a wheel, not shown.Springs 32 have one end connected to a locking plate 34 and the otherend connected to the respective shoes to urge them into contact with theanchor when the fluid motor is not pressurized. A parking brake leverarrangement, which constitutes part of the invention, is provided whichincludes a bell crank lever 36 operatively connected to an actuatingmeans, not shown, at one end and has a notched portion at the other end38 hearing against shoe web 40. The bell crank lever end 38 is furtherconnected to a strut 42 which is connected to shoe web 44. Rotation ofthe bell crank lever 36 spreads the shoes apart and into contact withthe drum 30. The above arrangement also has a conventional automaticadjusting mechanism comprising cable 46 and cable guide 48, lever 50 andspring the backing plate can be seen in greater detail.

52. The cable 46 is attached at one end to the locking plate 34 and hasthe other end connected to lever 59. The spring 52 has one end connectedto the shoe web 4% and the other end connected to the lever 50. Thelever 56 is pivotally connected to shoe web 44 at 54 and has a portion.56 engaging the toothed wheel 58. If the brake shoes require a greaterdistance than desired before contacting the brake drum, the cable 46will pivot the lever '0 so that the portion 56 will engage another toothof wheel 58. Upon release of the brake, spring 52 will return lever 56to ts normalposition thereby turning toothed wheel 58 through the leverportion 56. Spring 60 is compressed between the end of the pin 62 whichis attached to the backing plate md theweb of the brake shoe to helpmaintain the brake shoes in a laterally fixed location with respect tothe bac ing plate 10.

Backing plate With reference to FIGURES 26, the construction of Thebacking plate is stamped out of a flat sheet of metal and has a centralarea 64 raised relative to the outer periphery 66 of the backing plate.As can be seen, mtegralanchor 12 extends axially above the central areasurface 64. Pads 68 and 76 are slightly raised above the central surface64 and are slidably engaged by the webs 40, 44 of the brake shoes. Pads70 are closely adjacent the anchor 12, thus supporting the brake shoesclosely adjacent the anchor pin. The anchor 12 joins the central portionat neck 72 which is a minimum distance fromtheplane of force exerted bythe web ends 22, 24 of the brake shoes on the anchor when the brake isapplied. Actually, the depression of the neck 72 is below the plane ofpads 7t! a distance less than the thickness of the backing plate.Therefore only the minimum amount of bending moment is produced upon theanchor and the necessary designed strength of the anchor may besubstantially reduced. In a backing plate construction Where the ends ofthe shoes nearest the anchor are not supported in the above manner, saidends tend to pivot toward the backing plate (therefore the web ends arecloser to the backing plate than the center portion of thewebs of thebrake shoe) and slide axially toward the backing plate during the brakeapplication causing a detrimental effect on the anchor and brake shoebesides a dragging effect and slow release. Constructing the pads 70.closely adjacent the anchor allows the brake shoe ends 22, 24 to belocated axially to hear at right angles against the anchor when thebrake is applied and inherently provides a stronger construction in thearea of the anchor 12. Test results have shown that there issubstantially less deflection of the backing plate inthe anchor areawhen this construction is used.

FIGURES 6A-6C illustrate the different shapes of integral anchorprojections 312, 412 and 512. Only one shoejweb is shown forconvenience. The primary purpose of these shapes is to provideadditional support for the walls of the anchor projections. Preferably,but not necessarily, the rear surface 314, 414, 5140f each anchorisbelow the edge of the shoe web.

FIGURE 6D illustrates integral anchor projection 612 wherein slug 614 issheared from its dotted line position to .the full line position whereit provides better support forthe walls of the. projection 612.

FIGURES 6E and GF show chamfered plug 714 inserted into projection 712and plug 814 inserted into projection 812, respectively. The plugsprovide additional support for the walls of the projections.

FIGURE 6G illustrates a reinforcing plate 914 having a front portion9-16 thereof inserted into the integral anchor projection 912 and rearportion thereof resistance Welded to the backing plate 10.

FIGURE 6H illustrates a plug 130 inserted through the integral anchorprojection 132 of the plate. Plug 1.30

is. press fitted into position and may have anend 134 on which springsmay be mounted and a shoe guide plate may be mounted if the novel wheelcylinder mounting means of the present invention is not used inconjunction with the brake assembly.

Instead of having an integral anchor projection extending axially abovethe backing plate central portion 64, an anchor pin may be insertedthrough a hole punched in the center portion of the backing plate andwelded to the backing plate. FIGURES 6I-6N illustrate this constructionin different embodiments. In FIGURE 61 pin 23% has a lower portion 232inserted through opening 234 of backing plate 10. The flange 236 of pin23% is forced down against the backing plate 10 and this forces materialof the backing plate to flow into the groove 238 of pin 230 therebycreating an interlock between the pin 23% and backing plate 1-0. FIGURE6] discloses a pin 33% which has a front portion 332 inserted throughthe opening in the backing plate It and the lower portion 334 is weldedto the backing plate. The lower portion 334 is shown prior to welding.The anchor pins 430, 53%), 630 and 731) of FIGURES 6K-6N are insertedfrom the shoe end of the backing plate to the rear of the backing platewith the rear ends of the anchor pins 432, 532, 63 2 and 732 having theshape as shown in dotted lines. The last named rear ends of the anchorpins have been reshaped as shown in full lines and welded to the backingplate. FIGURES 6Mv and 6N illustrate the use of a reinforcing plate 634,and 734 in conjunction with the anchor pins 630 and 730. The reinforcingplates 634 and 734 are welded to the backing plate and the anchor pins639 and 730 are welded to their respective reinforcing plates. As can beseen by FIGURES 6I6N, the shoe webs are supported closely adjacent theanchor pins and the anchor pins may be of very short construction and donot withstand as much a bending stress as they would if they wereattached to a center portion of a backing plate which is not raisedaxially the same amount as that contemplated in the invention. Theanchor pins 230, 330, 430, 530, 630 and 73% may have axially extendingportions v at the front thereof for the same purpose as end 134 of plug130.

A shallow depressed area 74 is formedin the backing plate with a radialslot 76 formed therein. The area 74 is shaped as close as possible tothe outer periphery of the wheel cylinder 26 and the back of the area 74is kept as close as possible to the plane of the central area 64 to addto the strength of the backing plate in the area of the anchor 12. Thewheel cylinder or fluid motor 26 fits into the shallow depressed area ina manner to be described hereinafter. The outer periphery of the centralportion has recesses 78, one of which has a slot 80 therein depending onwhether the backing plate is for a right or left wheel. The slot 81receives a bell crank lever 36 which is operatively connected toa handbrake or parking brake actuator.

While the backing plate construction as illustrated is adapted for aservo type brake, the backing plate construction may be modified bymoving the wheel cylinder depression in the area approximatelydiametrically opposite the anchor.

Wheel cylinder connection to backing plate For explanation purposes, thefollowing terms, forward, upper, lower, downward, axial, radial, frontand rear, are used with a view of the following orientation of the brakeassembly: The shoe side of the backing plate is the front or forwardpart of the assembly; the anchor is located in the upper portionof thebacking plate; the axis of the brake drum is considered to define thedirection of axial movement; and a direction radial to the axis isconsidered as a radial direction.

Referring to FIGURES 7 and 7A, wheel cylinder 26 has flanges 82 and 83integral therewith and integral with the inlet and bleeder boss 84. Lugs82 and 83 extend laterally beyond the outer side periphery of the wheelcylinder 26. The wheel cylinder has a fiat portion 86 on one side andtwo spaced integral bosses 88 extending laterally outwardly from theupper portion of the same side as the flat portion 86, and has integralprojections 90 (see FIGURE 1) extending from the middle portion of thesame side. The wheel cylinder is connected to the backing plate by firsttilting the wheel cylinder toward the anchor 12 and inserting flange 82into the slot 76, which is slightly wider than the width of the inletboss 84, until surface 92 of the wheel cylinder bears against the upperedge 94 of the slot 76. Then, the lug 83 will fit into the slot with itssurface 96 moving past the lower edge 98 of slot 76. The wheel cylinderis then moved downwardly with the boots 99 hearing on portions 190 ofthe depressed area 74. It will be noted that due to the slant of thedepressed area 74, any down- Ward motion of the wheel cylinder willresult in the wheel cylinder camrning forwardly on the depressed areaand bringing lugs 82, 83 in contact with flat rear portions 162 and 104of the backing plate and tends to interlockingly locate the wheelcylinder relative to the backing plate in both radial and axialdirections. Locking plate 34 is inserted between the wheel cylinder andthe upper edge 94 of slot 76'and has a portion 197 bearing against thefiat surface 86 of the wheel cylinder. The locking plate has ears 106,one of which has a spring 32 and a cable 46 connected thereto and theother of which has a spring 32 connected thereto. While the springs 32and cable 46 are shown connected to the ears 1% of the locking plate,the springs and cable may be attached to the looking plate by othermeans, such as, for example, the locking plate having openings thereinfor receiving the springs and cable. Springs 32 maintain a bias on thelocking plate in a downward direction thereby urging the wheel cylinder74 in a downward and forward direction and engaging the lugs 82, 83 withthe rear portions 162, 1% of the backing plate. Lateral movement of theplate is limited by projections 90 (see FIGURE 1) of the Wheel cylinderand axial movement of the locking plate is limited by the bosses 83 ofthe wheel cylinder. The locking plate may also serve another function,that of preventing excess axial movement of the shoe ends 22 and 24 awayfrom the anchor by having laterally extending portions 108 overlying theshoe ends 22 and 24. \Vhether or not the locking plate has a portionextending over the shoe ends for preventing excess axial movement of theshoe ends depends on the type of brake assembly used. It will be notedthat the slot 76 also serves to locate both the wheel cylinder and thelocking plate 34 on the backing plate.

FIGURES 7B and 7C illustrate a modification of the wheel cylinder,backing plate connection of FIGURE 7 wherein a locking plate is notused. The wheel cylinder housing 27 has an inlet boss 85 with lugs 87and 89 forming a groove 91 interlocking receiving upper edge 94 of theslot 76. The wheel cylinder housing has cars 93 integral therewith forreceiving the ends of springs 32 and the end of the automatic adjustingcable 46. Rib 97 is integral with the housing and extending over theshoe ends 22, 24 of the brake shoes for preventing excess axial movementof the ends 2.2, 24. For an added safety feature, the wheel cylinderhousing 27 has a flange 161 integral therewith which bears against thedepressed area 74. The backing plate has a grease bafile 163 havingportion 105 extended to overlie the flange 1031 to prevent axialmovement of the wheel cylinder 27. A highly compressible sealing gasket1%7 is provided between the wheel cylinder and backing plate forpreventing water and dirt from entering the interior of the brakeassembly.

While the embodiments disclosed illustrate the springs 32 attached tothe brake shoes, they could be attached to any support which will serveto create a bias on the wheel cylinder. Furthermore, it is conceivablethat if the bias on the wheel cylinder by springs is undesirable, thetighter interlocking connection between the wheel cylinder and backingplate could be effected, for instance by inserting a strip of materialbetween the flange 96, lugs 82, 83 and the backing plate surface 102 andbetween the lug 87 and the backing plate surface 102.

While the wheel cylinder, backing plate connections are shown inrelation to a shoe web guided backing plate, the connection may be usedwith any type backing plate.

Parking brake Referring to FIGURES 8 and 9, the bell crank lever 36extends through a slot of the recess 78 and has a notch 119 formedtherein at the front end 38 of the lever. The notch of the bell cranklever receives the web 40 of the brake shoe. A strut 42 has one end 114connected to the web 44 of the brake shoe and is inclined frontwardly towhere its other end 116 is connected in front of the web 40 to end 38 ofthe bell crank lever 36. The rear end 118 of the bell crank lever has acable 120 connected thereto, which cable leads to a parking brake leveror hand lever, not shown. A rubber shield 122 is located interiorly ofthe backing plate to keep dirt from entering the brake assembly throughthe slot 80. The shield fits snugly over the end of the lever 38. Uponpulling the cable 125, the bell crank lever 36 will wedge the two brakewebs 40 and 44 apart through the notched portion 110 and strut 42 with aforce component tending to urge each shoe toward the backing plate.Spring 124 is connected to link 42 at end 114 and serves to hold thelink in place with relation to the web 44 and also serves to preventrattling of the link 42. Spring 1111 is inserted between end 38 of lever36 and web 40 of the brake shoe to hold the lever 36 in place andprevent rattling thereof.

FIGURE 10 illustrates a different embodiment of the invention where thebacking plate is secured to a spindle at the anchor. The integral anchor212 has a hole 214 therein receiving bolt 216 which secures the backingplate to the spindle 218.

Although this invention has been illustrated in connection with specificembodiments, numerous other inventions and adaptations of the inventionwill be apparent to those skilled in the art. I intend to include in thescope of the following claims all equivalent applications of theinvention whereby the same or substantially the same results may beobtained.

1 claim:

1. In a brake assembly, a backing plate having an opening therein, awheel cylinder provided with a boss received in said opening, and alocking member having a portion thereof extending into said openingbetween said wheel cylinder boss and an edge of said opening fordetachably securing said wheel cylinder to said plate.

2. The structure as recited in claim 1 wherein said brake assembly hasbrake shoes with opposing ends, said locking member having anotherportion extending over said opposed ends of said brake shoes therebypreventing excess axial movement of said ends.

3. The structure as recited in claim 2 wherein spring means is connectedto at least one of said brake shoes and operatively connected to saidwheel cylinder.

4. An elongated housing for a wheel cylinder of a brake assembly, saidhousing having an integral lug extending outwardly from at least onelongitudinal side at the lower portion thereof, said housing having twospaced bosses integral with and extending outwardly from the upperportion of said side, said side having further integrally therewith twospaced projections extending outwardly and located between the upper andlower portion of said side, each of said spaced projections beinglongitudinally spaced from the center of said side a greater distancethan its respective closest one of the spaced bosses.

5. In a brake assembly, a backing plate having an opening therein, afluid motor housing located on the front of said backing plate andhaving a boss extending from the rear thereof through said opening, atleast one lug extending from a peripheral portion of said boss andlocated opposite a portion of the rear face of said backing plate, atleast a portion of the edge of said opening being spaced from acorresponding peripheral portion of said boss, and a locking memberinserted in said space to secure and maintain said fluid motor inposition on said backing plate.

6. The structure asrecitedin claim further including means formaintaining said locking member in position.

7. The structure as recited in claim '5 wherein said last narned meansincludes coacting surfaces on said fluid motor housing and said lockingmember.

"8. In a brake assembly, a-backing plate having an opening therein, aWheel cylinder disposed on the front face of 4 said backing plate, saidWheel cylinder being provided with a boss received in said opening, andmeans including a flange on said bossfor detachably mounting said wheelcylinder to said.plate,said flange engaging the rear face of saidbackinglplate, said assembly further including brake shoes With opposingends, said Wheel cylinder having a portion extending over said opposingends of said brake; shoes thereby'preventing excess axial movement ofsaid shoes.

8 9. The structure as recited in claim 8 further comprising spring meansoperatively connected to at least one of said brake shoes and to saidlast named portion of said Wheel cylinder for imparting a force on saidlug urging the same into engagement with said rear face of said backingplate.

References Cited by the Examiner UNITED STATES PATENTS 1,896,452 2/1933Loughead 18878 1,940,022 12/1933 Schnell 188106 2,057,724 10/1936 LaBrie 188106 2,152,066 3/1939 La Brie 188152 2,541,551 2/1951 Schnell188152 2,637,417 5/1953 House 188152 2,815,830 12/1957 OsWalt 188-2l6 X2,902,118 9/1959 Parker 18878 2,938,349 5/1960 Britton 54.6 3,136,3906/1964 Zukowski 18878 MILTON BUCHLER, Primary Examiner.

A. JOSEPH GOLDBERG, ARTHUR L. LAIPOINT, RALPH D. BLAKESLEE, EUGENE G.BOTZ,

Examiners.

1. IN A BRAKE ASSEMBLY, A BACKING PLATE HAVING AN OPENING THEREIN, AWHEEL CYLINDER PROVIDED WITH A BOSS RECEIVED IN SAID OPENING, AND ALOCKING MEMBER HAVING A PORTION THEREOF EXTENDING INTO SAID OPENINGBETWEEN SAID WHEEL CYLINDER BOSS AND AN EDGE OF SAID OPENING FORDETACHABLY SECURING SAID WHEEL CYLINDER TO SAID PLATE.